It is known to provide wall ventilator constructions with closure louvers or shutters associated with a temperature-responsive spring which operates to move the louvers and control flow of air through the ventilator. U.S. Pat. Nos. 3,436,061 and 3,528,606 disclose temperature-responsive foundation wall ventilators comprising a housing defining an air flow passageway containing a plurality of parallel, side-by-side louvers pivotally mounted for simultaneous movement to open and close the passageway, and operatively connected to a bimetallic temperature-responsive coil spring which expands or contracts in response to temperature changes to simultaneously pivot the louvers between open and closed positions. In U.S. Pat. No. 3,436,016, the coil spring is located in the air flow passageway of the ventilator in a central opening in one of the louvers, with the inner end of the coil spring attached to a stationary support rod for the louver, and the outer end attached directly to the face of the louver. The louvers are operatively interconnected and are pivotally moved by temperature changes which cause expansion or contraction of the spring. In U.S. Pat. No. 3,528,606, the coil spring is located in an enclosed box on one side of the ventilator air flow passageway, with the inner end of the spring being fixed to the ventilator housing by a bolt, and the outer end of the spring being operatively attached to a member which interconnects the louvers for simultaneous movement.
U.S. Pat. No. 4,175,480 discloses a wall ventilator construction having a temperature-responsive spring located in the housing air flow passageway in a central opening of one of the louvers. The spring is operatively attached to a stationary rod and to the face of the louver to simultaneously rotate the louvers in response to temperature changes. The ventilator has a flanged front frame attached by pins to the housing to overlie the periphery of a foundation wall opening, and the patent discloses that the ventilator housing may be formed of molded plastic.
My U.S. Pat. No. 4,210,279 discloses an automatic temperature-responsive ventilator wherein the temperature-responsive spring is located in a side wall opening of the ventilator housing within a retainer-protector cap secured in the opening. One end of the spring resides in a slot in the periphery of the wall opening and the other end of the spring is received in a slotted rod which extends into an opening in one of the louvers of the ventilator to move the louvers in response to contraction and expansion of the spring.
My aforesaid copending U.S. patent application Ser. No. 69,243 filed Aug. 23, 1979, now U.S. Pat. No. 4,243,175, the disclosure of which is incorporated herein by reference, discloses a temperature-responsive ventilator construction comprising a housing of molded plastic defining an air flow passageway containing a plurality of movable louvers which are interconnected for simultaneous pivotal movement to control the flow of air through the passageway. Operation of the louvers is controlled by a temperature-responsive elongate, helical spring, one end of which is attached directly to the face of one of the louvers and the other end of which is slidingly received on a stub shaft which is received within an opening in a side wall of the housing. The periphery of the side wall opening and the peripheral surface of the stub shaft are of notched configuration. Tension on the spring may be adjusted manually by rotation of the stub shaft in the side wall opening, so that the ventilator louvers may be initially set to open and/or close at a desired air temperature.